The present invention relates in general to a method of, and apparatus for driving tunnels or other excavations all referred to hereinafter for convenience as "tunnels."
It is known to produce tunnels with the aid of a drive shield composed of drive members or cutters supported on a frame and advanced in succession by hydraulic rams. Various techniques have been adopted to facilitate support of the resulting tunnel wall and the formation of a permanent lining for the tunnel wall. Thus, it is known to provide each drive member of the drive shield with a rear extension sometimes called a rear tail. These rear extensions form a rear protective shield which supports the wall between the drive shield and the lining. As the rear extensions are moved up temporary or preliminary support is provided for the wall. To this end it is known, especially with loose soil, to seal the wall exposed by the rear extensions with the aid of a sealant, usually sprayed fluid concrete, which may form part of the final support lining. It is also known to introduce arches or rings into the rear shield to facilitate the support of the rear extensions and the tunnel wall.
A general object of the present invention is to provide an improved method and apparatus for driving tunnels.